A known orbital abrading or polishing tool includes a motor having a rotor which rotates inside a motor housing. The rotor transmits a rotational force to a carrier part having an abrading or polishing head attached thereto. A key typically extends from the carrier part and engages a keyway in the rotor, such that rotation of the rotor causes a corresponding rotation of the carrier part and the abrading or polishing head. Compressed air enters the motor housing through the inlet passage and causes the rotor to rotate within the motor housing. As the rotor rotates, vanes slide in and out of slots in the rotor, creating sealed chambers or compartments between adjacent vanes. As the compressed gas expands within these compartments, it pushes on the vanes, causing the rotor to rotate and the vanes to slide in and out of their vane slots. The expanded air is then exhausted through one or more exhaust passages in the motor housing, and the process is repeated.
Each vane slides partially out of and then back into its rotor slot every time the rotor makes one complete rotation. When the rotor spins at very high speeds, the vanes slide in and out very quickly. As a result, the vanes can wear down the surface of the vane slots formed inside the plastic rotor. The wearing of the vane slots produces debris in the rotor housing which can further abrade the vane slots and the vanes themselves. After a certain amount of time, the vane slots are abraded to such an extent that they cannot contain the vanes as they slide rapidly in and out of the slots, and the plastic rotor fails and has to be replaced.
Accordingly, there is a need for an improved rotor with a wear-resistant vane slot.